The number of teenagers sent to emergency rooms more than quadrupled after marijuana was legalized in Colorado — mostly for mental health symptoms, researchers reported Thursday.
They found 639 teenagers who went to one hospital system in Colorado in 2015 had either cannabis in their urine or told a doctor they'd been using cannabis. That's up from 146 in 2005, before the use of marijuana was legalized in Colorado.

One such statistic is a spike in calls to poison control centers. According to the National Poison Data System, calls about accidental ingestion of marijuana in children 9 and younger more than tripled in states that decriminalized marijuana before 2005. In states that enacted legalization from 2005 to 2011, calls increased nearly 11.5 percent per year. Over the same period in states without decriminalization laws, the call rate stayed the same.